Because of their large numbers and ease in harvesting, fish not only constitute an important food source for mankind, but also provide an important sport. Recreation fishing is enjoyed throughout the world, and artificial lures and bait have become an important tool in the arsenal of the angler.
In the past, lures have been constructed of many different materials, such as of silk, skin, feathers, wood, metals and the like. With the advent of easily formed plastics, it has been relatively easy to fashion lures to imitate bait such as shrimp, frogs, insects, fish, worms and the like. One of the latest trends in lure construction is to provide forms which more closely resemble live creatures that arouse the curiosity and rapacity of the fish.
Many of these plastic lures are characterized by long, thin ribbon tails that are curved or shaped to present wiggling or undulating simulated swimming action in the water in order to further attract fish to the lure. A variety of tail shapes, sizes, and thicknesses are currently used in many of the plastic fishing lures on the market today. Typical of the plastic fishing lures used with good success in catching black bass, small mouth bass, and other game fish is the "curly tail" lure having one or more tail segments extending therefrom and curled inwardly or outwardly to a thin ribbon-like point. When the lure is put into the water, the tail undulates or folds and unfolds as it "swims" through the water to attract fish. As described in the Garst Patent No. 5,465,523 entitled "Undulating Single Tail Fishing Lure," lures of this type are shaped from a plastic material that can be easily injection molded in a variety of colors and shapes. Desirable odors can even be synthesized and provided in the lure bodies. Other lures, similar in form, are characterized by a "moving ribbon" appearance as they are drawn through the water.
It is to be noted from the Garst patent that this patentee provides a lure of U-shaped configuration which tends to straighten as it is drawn through the water, but concerning which this patentee says nothing about the fin of his lure undertaking a desired rippling on such occasion. Patentee Garst describes that his lure has a generally triangular cross section with a tall apex and a short base, with the sides of the lure slightly curved in a concave manner. Obviously Garst does not teach a lure having a flexible, elongate dorsal fin that is essentially flat and relatively thin, which is capable of undertaking a pronounced degree of rippling even when it is moved through the water at low speed.
The Hill Patent No. 4,138,792 entitled "Artificial Snake-Eel Body" describes a lure involving an elongate strip member of multi-convolution spiral configuration, which decreases in radius of curvature toward the rear end thereof. The strip is of greater transverse width than thickness and one longitudinal edge of the strip comprises the inner periphery of the spiral and the other longitudinal edge of the strip comprises the outer periphery of the spiral. This patentee sets forth that the strip is constructed of resilient, flexible material and includes, on its large radius of curvature end, an endwise outwardly projecting terminal end portion extending generally axially of the spiral of the strip and intended to simulate the head of a swimming snake or eel. The strip, when moved forwardly through the water, is stated to undulate in the manner of a swimming snake or eel and the patentee states that the "swimming action" thereof is difficult to distinguish from the undulating swimming movement of a snake or eel.
It is most important to note that patentee Hill states in the mid portion of Column 1 of his patent that his elongated strip is constructed of shape retentive flexible material, but it is to be noted that for Hill's strip to be shape retentive is really an undesirable characteristic rather than being a desirable attribute.
One of the problems with constructing a lure having relatively thin fins that ripple in a realistic manner while passing through the water is the expense of creating rippled fins on such a lure. Some manufacturers have created lures with elongate fins having preformed ripples, with these ripples being created by utilizing a pair of interfitting molds carefully configured to form such preformed ripples, but such molds are necessarily expensive to construct.
It is to be noted that neither patentee Garst nor patentee Hill describe the specific configuration of the molds used in the creation of their lures, nor do they explain the particular circumstances under which molding efforts take place.
Many prior art patents relating to injection molding are in existence, and these include the Neuman Patent No. 4,021,515 entitled "Plastic Injection Mold with Self-Adjusting Coring Apparatus"; the Kluge Patent No. 4,437,257 entitled "Foamed Plastic Fishing Lure Body Having a Controlled Density and a One-Piece Wire and a Method for its Manufacture"; the Jaroschek Patent No. 5,090,886 entitled "Apparatus for the Injection Molding of Fluid-Filled Plastic Bodies"; and the Sugiyama et al Patent No. 5,295,801 entitled "Mold for Hollow Injection Molding."
The Littleton Patent No. 4,969,811 entitled "Apparatus for Making Plastic Devices" reveals that it is known to mold plastic fishing lures from suitable plastic utilizing various types of molds. The Littleton patent is not truly consequential to the present invention, however, for it is concerned with the molding of lures having skirts of stranded plastic. Nevertheless, the Littleton patent shows the use of mold cavities involving male and female mold components that cooperate in such a manner that a number of lures having stranded skirts can be molded at one time by the use of a suitable plastic heated to a proper molding temperature.
None of these patents addresses the problems necessarily involved in creating molds that are effective in the injection molding of lures possessing a dorsal fin having molded or built-in ripples.
It is well known that in the molding of plastic fishing lures, upper and lower interfitting molds are utilized, with each mold half being responsible for creating one half of the lure or lures being made each time hot plastic is injected into the contiguous mold halves. Many molds are circular, and enable twelve to eighteen, possibly even more plastic lures to be molded at a time. As is obvious, the contours of the upper mold half must closely match the contours of the lower mold half if lures are to be created that will be attractive enough to be purchased by fishermen. In other words, one mold half must be the mirror image of the other mold half.
In the typical instance, there is a "parting line" or surface plane that is consistent across the entire width of each mold half, but this generality does not closely apply when molds have been created for the injection of lures having built-in or preformed ripples. Starting for example with the lower mold, for one part of a ripple there must be an upwardly curving protrusion extending above the parting line, which is followed by a downwardly curving recess. This downwardly curving recess is then followed by another upwardly curving protrusion above the parting line, which is followed by another downwardly curving recess, and so forth, with this continuing for the length of the rippled fin being created.
Because a pair of molds is involved in the above example for the injection molding of plastic lures, there must necessarily be a properly shaped curved recess in the upper mold corresponding to each upwardly curving protrusion of the lower mold, and quite importantly, there must also be a downwardly curving protrusion on the upper mold directly above each of the downwardly curving recesses of the lower mold. Each of the curving protrusions of the upper and lower molds must necessarily extend beyond the parting line of each mold, and it is manifestly true that each of these protrusions must closely match the inwardly curving recesses of the other mold half if a fin of a desirable, consistent thickness is to be created on each lures.
It is thus to be seen that in order to be able to create a lure having a rippled fin, it would be necessary for there to be several protrusions extending beyond the contours of each mold half, or in other words, these protrusions must extend beyond the parting line of each mold.
The service of a skilled programmer as well as the service of a skilled machinist are necessary for the creation of complex mold halves of this type, with it being necessary for the programmer to start out by writing a program setting forth the specifications of the size of the lure body as well as the specific configuration of the rippled fin that is to form an integral part of the lure body. After the program has been written, the programmer goes to the Computer Numerically Controlled Millport (CNC Millport) in order to actually cut the cavity, typically out of aluminum plate.
The program prepared by the programmer is given to the machinist, who cuts a single cavity prototype, involving top and bottom mold halves. Because the upward protrusions from the lower mold and the downward protrusions from the upper mold necessarily cross the parting line of each mold half if built-in ripples are to be created in the fin of the lure, it is obviously necessary for a considerable amount of aluminum of the plate or disk to be milled away in order to create each mold half. The milling cutter must undergo wide excursions in order to not only remove aluminum for the creation of each cavity in which a lure is to be created, but also to cut the correct arc on each protrusion extending above the parting line of the mold half. Because the parting line must be crossed in both directions by the milling cutter in order to create the several protrusions and the several recesses to be formed in each mold half, it is obvious that much more aluminum must be milled away from each mold half than was involved in the creation of a typical lure in which molded fins were not required. It is also obvious that great care be taken in matching the protrusions and recesses of one mold half with the recesses and protrusions of the other mold half if the rippled fins are to be of a desired thickness.
The milling away of metal on each mold half becomes a very tedious effort, and even an experienced programmer-machinist team will typically need to create eight or so prototypes before suitably accurate mold halves have been evolved, as will enable finished lures to be molded. As an example of cost, each prototype typically costs in the vicinity of $400.00 in programming time, in addition to which is the expense of the aluminum disks.
Numerous prototype lures are made, with the contours of each lure being carefully checked, until finally a lure having a rippled fin of the desired thickness and desired configuration has been created. Once this has been accomplished, it is then possible to create carefully interfitting mold halves that will bring about the simultaneous creation of a dozen or more lures each time hot plastic is injected between the mold halves.
In sharp contrast to the construction of mold halves enabling the creation of lures with built-in ripples of their fins, mold halves responsible for creating lures whose fins are not initially rippled are much less expensive to make inasmuch as no protrusions extending beyond the parting line of the molds are involved.
It was in an effort to overcome the prohibitive cost associated with the creation of molds able to make lures with built-in or preformed ripples that the present invention was evolved.